Discharge tube



June 5, 1934. Y ET AL 1,961,696

DISCHARGE TUBE Filed 001;. 5. 1929 INVENTORS DRK LELY AND BY G.VAN BEUSEKOM Patented June 5, 1934 DISCHARGE TUBE Dirk Lely and Godefridus van Beusekom, Eindhoven, Netherlands, assignors to Radio Corporation of America, a corporation of Delaware Application October 5, 1929, Serial No. 397,469 In the Netherlands October 27, 1928 2 Claims.

If discharge tubes are used for certain purposes the electrodes of these tubes are to be connected to diverse elements such as resistances, condensers, and the like. The nature and size of these elements depend on the purpose served by the tube but for each particular purpose they are rather fixed. If, for example, it is desired to heat the filament of a radio valve directly with alternating current, the potentiometer has generally to be connected in parallel with the filament, it being necessary in this case in order to avoid undue coupling that the tapping point of the potentiometer should be connected through a condenser to one of the filament ends. The combination of potentiometer and condenser is a portion of the circuit arrangement which is almost fixed for this case and which is to be added to each of the valves to be thus heated.

Another example is that of a radio valve which has to operate in the usual detector circuit arrangement (grid detection). The grid of such a valve must be connected to one of the coatings of a grid condenser and to one of the ends of a leak the other end of which is connected to an intermediate tapping point of a potentiometer which is connected in parallel to the filament. Consequently in this case the combination gridcondenser-leak potentiometer is to be connected to the valve. It is also possible to omit the potentiometer and to connect the leak in parallel to the condenser. In this case however, when establishing the connections due regard is to be had to the polarity of the filament ends, Whereof we are independent when connecting the leak holes for the passage of the contact plugs of the valve.

The sleeve may be provided with one or more resilient contacts which are caused to bear on the particular contact plugs of the valve when the latter are slipped in the sleeve. The invention has a double advantage in that it results in a saving in time when mounting and a saving in space.

The former advantage will be obvious. In fact it is only necessary to slip the sleeve with the combination mounted thereon on the lamp cap until the bottom of the sleeve engages the under surface of the cap and then to insert the valve in the usual manner with its plugs projecting into the contact plungers of the valve foot, all of which can consequently be carried out in a few seconds.

As regards the latter advantage it may be ob served that the sleeve is caused to be located entirely within a space which previously was to be considered as wasted.

Indeed, as a rule which Figure 1 is a diagram of a high frequency valve heated with alternating current.

Figure 2 is a normal audion circuit arrangement.

Figure 3 shows an example of an auxiliary device embodying the invention.

The high frequency amplifier shown in Figure 1 comprises a valve V, the grid G and cathode F which have connected between them a tuned circuit.

The filament is heated by alternating current supplied from a transformer T. The filament has connected in parallel to it a potentiometer P the central tapping point of which is connected through a condenser C to one of the filament ends.

The object and the operation of these members are assumed to be well-known.

The back-coupled audion shown in Figure 2 comprises a valve V, the grid G of which is connected to one of the coatings of a grid condenser C and to one endof a leak L. The

other end of this resistance is connected to the central tapping point M of a potentiometer P the ends of which are connected to the poles of the filament F.

The auxiliary device shown in Figure 3 for housing the elements to be connected to a valve comprises essentially a small sleeve S which is of insulating material, for example of the material known under the registered trade mark bakelite and which is adapted to be slipped over the cap B of a radio valve or other discharge tube.

For this purpose the bottom of the sleeve ed to admit these plugs.

The sleeve is external- 1y provided with a number of grooves, in the case shown with two grooves, adapted to receive the elements to be connected to the valve. An auxiliary device for a circuit arrangement as shown in Figure 1 is illustrated on the drawing. The sleeve S is provided with a condenser C constructed as a wound condenser, and with a potentiometer P the central tapping point of which is constituted here by a small binding screw M which is secured in the Wall of the sleeve.

The underside of the sleeve has fixed to it two contacts X and Y which are connected respectively to the two ends of the potentiometer and which bear on the contact plugs F1 and F2 which constitute the poles of the filament of the valve. The two coatings of the condenser C are connected respectively to M and to one of the ends of the potentiometer.

If for a circuit arrangement as shown in Figure 2 a corresponding auxiliary device is desired, the condenser C may be housed in the upper groove and the leak L together with the potentiometer P in the lower groove. The contacts X and Y remain connected to the ends of the potentiometer the centre of which is, however, not caused to bear on the binding screw of the sleeve but to one end of the leak. The condenser C is partially connected to the other end of the said leak and partially to the said binding screw.

The elements necessary for resistance amplification may likewise be mounted conveniently on an auxiliary device according to the inven-- tion while preserving entirely the above advantages.

We claim:

1. In a discharge tube amplifying system wherein certain impedance elements are connected directly to various electrodes of the tube a non-conducting uni-laterally closed sleeve adapted to completely envelope the base of said tube having perforations therein for admitting therethrough the contact plugs of the tube, an impedance supported by and constructed around said sleeve, a second impedance constructed around and supported by said sleeve, means for connecting one terminal of one of said impedances to a terminal of the other, a spring contact device connected to the free terminal of said first named impedance adapted to contact with a predetermined one of said tube plugs and a second spring contact device connected to the free terminal of said other impedance adapted to connect said free terminal to another predetermined tube plug.

2. As an article of manufacture, a sleeve adapted to form an enclosure for a discharge tube base, a plurality of perforations in said sleeve adapted to admit therethrough contact plugs of a discharge tube, an impedance element mounted upon said sleeve, contact means mounted on said sleeve connected to a terminal of said impedance and adapted to connect said impedance element to a tube contact plug passed through one of said perforations and a second contact device supported by said sleeve connected to an intermediate point of said impedance.

DIRK LELY. GODEFRIDUS VAN BEUSEKOM. 

